feat: Support dot notation on array fields

[dplewis]

Pull Request

• Report security issues confidentially.
• Any contribution is under this license.
• Link this pull request to an issue.

Issue

Currently all dot notations are treated as operations on Object type field. This results in a error: Cannot read property '0' of undefined when used on Array type fields.

Closes: #6687

Approach

• Check types for Array vs Fields based on dot notation format.
• If dot notation is used prevent array to object conversion

https://www.mongodb.com/docs/manual/core/document/#dot-notation

Tasks

• Add tests
• Add changes to documentation (guides, repository pages, code comments)
• Add security check
• Add new Parse Error codes to Parse JS SDK

[parse-github-assistant]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.77%. Comparing base (2ecc5a5) to head (7e57ccb).

Additional details and impacted files

@@            Coverage Diff             @@
##            alpha    #9115      +/-   ##
==========================================
- Coverage   93.78%   93.77%   -0.02%     
==========================================
  Files         186      186              
  Lines       14729    14737       +8     
==========================================
+ Hits        13814    13820       +6     
- Misses        915      917       +2     

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[dplewis]

@mtrezza This is an extremely complicated feature. I tried running this with the SDK internal fix against the server test suite and got Array dot notation working but it somehow broke the server. I’ll let you know when this is ready for review.

[dplewis]

@mtrezza This is ready for review.

[mtrezza]

• Hard-coded field names look suspicious. If certain fields require special treatment for this logic to work we may end up with the same issue as in Object attributes transformed in array Parse-SDK-JS#2198.

• Maybe we should be stricter than isNaN, from Object attributes transformed in array Parse-SDK-JS#2198 I suspect there may be edge cases where this logic fails. Without using regex (too expensive) the only solution I can think of is on a per char basis; not sure about its perf though:

  const isArrayIndex = Array.from(y).every(c => c >= '0' && c <= '9')
  

[dplewis]

I added the stricter array index check.

The hard coded field names come from the _PushStatus schema. They have array indexes but are saved as objects instead of arrays.

[mtrezza]

They have array indexes but are saved as objects instead of arrays.

What does that mean? Is this the issue discussed in parse-community/Parse-SDK-JS#2198 (comment) where we don't know whether an object key 0 is an array index or a normal object key? I have rebased this PR to include the tests added in #9179. Let's see how that goes.

[mtrezza]

The tests pass, that's a good sign. What would we have to change for the push status so we don't have to treat them differently here?

[dplewis]

Pretty much nothing we can do here. These are built into Parse instead of created by the user. This wouldn't break anything as the fields are type Object in the schema and are still type Object after this PR.

If you want to see how it works check out this test

https://github.com/parse-community/parse-server/blob/alpha/spec/PushWorker.spec.js#L324